Reversible air-punching mechanism for making holes in soil by compaction

ABSTRACT

The invention relates to reversible air-punching mechanisms for making holes in soil by compaction. According to the invention, the mechanism comprises a hollow housing in which a striker reciprocated by compressed air, strikes the housing and thus moves it through the ground. The compressed air is delivered into the working chambers through an air-feed bushing which is provided with two rows of ports getting alternately in line with the corresponding rows of ports in the hollow slide valve accommodated in the bushing as said slide valve turns around its longitudinal axis. For turning the slide valve, it is connected with the bushing by a projection which moves along an enclosed shaped recess during the reciprocating motion of the slide valve when the mechanism is reversed by cutting off momentarily the supply of compressed air to the mechanism.

United States Patent 11 1 Sudnishnikov et al.

[ 1 Apr. 17, 1973 [54] REVERSIBLE AIR-PUNCHING MECHANISM FOR MAKING HOLES IN SOIL BY COMPACTION [75] Inventors: Boris Vasilievich Sudnishnikov,Alexandr Dmitrievich Kostylev, Konstantin Stepanovich Gurkov, Konstantin Konstantinovich Tupitsyn, Vladimir Dmitrievich Plavskikh, all of Novosibirsk; Viktor Eliseevich Solomko, Alexandr Mironovich Reinsburg, both of Odessa, all of USSR.

[73] Assignee: Institut Gornogo Dela Sibirskogo Otdelenia Akademii Nauk SSSR, USSR, Novosibirsk Krasny prospekt [22] Filed: Feb. 8, 1971 [2|] Appl. No.: 113,291

52 us. (:1. ..173/91, 91/33, 91/234, 175/19 51 Int. Cl. ..E2lb 3/12 [58] Field of Search ..l73/91 [56] References Cited UNITED STATES PATENTS 3,407,884 10/1968 Zygmunt et a]. 173/91 FOREIGN PATENTS OR APPLICATIONS Primary Examiner-Ernest R. Purser Attorney-Eric Waters, John G. Schwartz and J. Harold Nissen, Roditi [5 7] ABSTRACT The invention relates to reversible air-punching mechanisms for making holes in soil by compaction.

According to the invention, the mechanism comprises a hollow housing in which a striker reciprocated by compressed air, strikes the housing and thus moves it through the ground.

The compressed air is delivered into the working chambers through an air-feed bushing which is provided with two rows of ports getting alternately in line with the corresponding rows of ports in the hollow slide valve accommodated in the bushing as said slide valve turns around its longitudinal axis. For turning the slide valve, it is connected with the bushing by a projection which moves along an enclosed shaped recess during the reciprocating motion of the slide valve when the mechanism is reversed by cutting off momentarily the supply of compressed air to the mechanism.

1 Claim, 4 Drawing Figures 11/1969 Great Britain ..173/9l PATENTEDAPRIYW 2 3.727. 701

SHEET 2 OF 2 REVERSIBLE AIR-PUNCI-IING MECHANISM FOR MAKING HOLES IN SOIL BY COMPACTION The present invention relates to the reversible airpunching mechanisms for making holes in soil by compaction and can be utilized, say, for laying underground conduits by the ditchless method.

The earlier application of the same Applicant claims a reversible air-punching mechanism comprising a hollow housing with a pointed head, said housing accommodating a striker which is reciprocated by compressed air and strikes the housing thus moving it through the soil.

The compressed air is fed into the variable-volume working chambers, the front chamber located between the inside surface of the housing and the external surface of the striker, and the rear one located inside the tail section of the striker and communicating with the front working chamber through the ports in the striker tail section.

The rear chamber communicates with the source of compressed air through a stepped air-feed bushing located in the rear chamber of the striker and secured by its flange in the tail section of the housing. The larger-diameter step of the air-feed bushing interacting with the striker has ports which are covered during the forward stroke of the mechanism by the slide valvelocated inside the bushing. The slide valve is rigidly connected with a spring-loaded sleeve which is installed on the smaller-diameter step of the bushing and is movable in the axial direction.

The known mechanism is reversed from the forward (working) operation to the reverse (idle) operation by reducing the pressure of the compressed air below the nominal value while the next reversal of the mechanism for the forward operation is ensured by raising the pressure of compressed air to the nominal value. In both cases changes of the air pressure cause the springloaded slide valve to reciprocate axially thus uncovering or covering the ports of the air-feed bushing and changing the delivery of compressed air into the front chamber. This reverses the direction of the striker blows dealt to the housing and, as a consequence, changes the direction of the moving mechanism as a whole.

The experience gained in operating these reversible air-punching mechanisms has shown that it is sometimes impossible to maintain the required pressure during the forward and reverse operation of the mechanism the pressure difference reaching 2-3 atm. Therefore, possible pressure fluctuations may result in an uncontrollable shifting of the mechanism from the forward to the reverse travel and vice versa in accordance with the above-described operating principle ofthe known mechanism.

Besides, it became clear that for easier penetration of the housing into the soil at starting it is necessary to operate the mechanism for some time at an air pressure below nominal which cannot be provided for by the design of the known mechanism described above.

Another disadvantage of the known mechanism consists also in the necessity of using the spring of a strictly definite stiffness.

An object of the present invention resides in eliminating the aforesaid difficulties and disadvantages.

The main object of the invention is to provide a reversible air-punching mechanism operating in forward and reverse directions at any required pressure in the airline.

According to the invention, this object is accomplished by providing the larger-diameter step of the airfeed bushing with a second row of ports, said second row being parallel to the first row of ports, and with air exhaust holes located on the face surface of the largerdiameter step while the hollow slide valve step interacting with the bushing also has two rows of ports separated from each other by a partition, these ports getting alternately in line with the corresponding ports in the bushing on turning of the slide valve for which purpose the slide and the bushing are interconnected by a projection moving along an enclosed shaped recess which ensures unidirectional turning of the slide valve around its longitudinal axis while said slide valve reciprocates axially during reversal of the mechanism by turning on and off the supply of compressed air to the mechanism. 7

It is practicable that the side walls of the enclosed shaped recess made on the internal surface of the bushing flange would be outlined by identical zig-zag lines in which each apex of the line would be displaced from the corresponding counter-opposed apex of the other zig-zag line through an angle ensuring the turning of the slide valve in one direction.

Such a design of the air-feed bushing and slide valve, according to the invention, prevents uncontrollable changes in the direction of travel of the mechanism regardless of any possible fluctuations of pressure in the compressed air line. This is attributed to the fact that change in the direction of the moving mechanism can be made only by turning on or off the supply of compressed air and thus actuating the slide valve which changes the delivery of compressed air into the front chamber ofthe mechanism thereby reversing the latter.

Other objects andadvantages of the invention will become apparent'from the detailed description of the invention that follows and from the accompanying drawings (in which:

FIG. 1 is the main diagram of the reversible airpunching mechanism for making holes in soil, a side view, partly cut away;

FIG. 2 is a section taken along line IIII in FIG. 1;

FIG. 3 is a section taken along line IIIIII in FIG. 1;

FIG. 4 is a developed view of the shaped recess along diameter d in FIG. 1).

The mechanism comprises a hollow cylindrical housing 1 (FIG. 1) with a pointed head, said housing accommodating a striker 2 which rests on the inside surface of the housing I by two bands 3 and 4. The space between the inside surface of the housing 1 and the external surface of the striker 2 forms the front working chamber 5 of a variable volume, said volume depending on the position of the striker 2 in the housing 1.

The tail section of the striker 2 also has a space which forms the rear working chamber 6 of a variable volume. The walls of the tail section of the striker 2 have ports 7 which, depending on the position of the striker 2, communicate the front chamber 5 either with the rear chamber which is constantly under pressure, or with the atmosphere.

Compressed air is fed into the rear chamber 6 through stepped air-feed bushing 8 whose flange 9 is secured in the tail section of the housing 1 and which is connected with the compressed air hose 10 from the compressor (not shown).

The cylindrical surface of the larger-diameter, steps of the bushing 8 interacting with the tail section of the striker 2, has two parallel rows 11 (FIG. 2) and 12 (FIG. 3) of ports while the face surface of this step of the bushing 8 is provided with holes 13 (FIG. 1) for the discharge of the used air. The discharge holes 14 are also provided in the flange 9 of the bushing 8.

Located inside the air-feed bushing 8 is a hollow slide valve 15 of the stepped cylindrical shape matching with that of the bushing 8. The cylindrical surface of the larger-diameter step of the slide valve 15, interacting with the bushing 8, also has two rows 16 (FIG. 2) and 17 (FIG. 3) ofports.

These rows 16 and 17 of ports are separated by an end partition 18 of the slide valve 15 and are so arranged that, once the slide valve 15 has turned through a preset angle (1 or 0 (FIG. 4), each row 16 and 17 of the ports gets alternately in line with the rows 11 and 12, respectively, of ports in the bushing 8. A spring 19 is installed between the face surface of the bushing 8 and the end partition 18 of the slide valve 15.

The inside cylindrical surface of the flange 9 of the bushing 8 is provided with an enclosed shaped recess 20 for the movement of the projection 21 located on the external surface of the tail section of the slide valve 15.

The side walls 22 and 23 (FIG. 1) of the shaped recess 20 have a contour formed by zig-zag lines 24 (FIG. 4) and 25, the apices 26 of the zig-zag line 24 and the corresponding counter-opposed apices 27 of the zig-zag line 25 being offset from one another through an angle a. This offset of the apices 26 and 27 of the zig-zag lines 24 and 25 which form the counter of the side walls 22 and 23 of the enclosed recess ensures unlateral turning of the reciproctin g slide valve.

The mechanism operates as follows.

During forward operation of the mechanism the compressed air entering the rear working chamber 6 through the channel of the slide valve 15 from the hose l0 shifts the slide valve 15 to the extreme right position (in FIG. 1). The ports in the row 1 1 of the bushing 8 are covered by the slide valve 15 (as shown in FIG. 2) and the ports in the row 12 of the bushing 8 get in line with the ports in the row 17 of the slide valve 15 (as shown in FIG. 3). The spring 19 will be compressed. Simultaneously, the compressed air admitted into the rear chamber 6 will shift the striker 2 to the left and it will strike the inside wall of the housing head thereby moving the entire mechanism forward in the soil, i.e. in the direction of the blow (to the left in FIG. 1).

The backward movement of the mechanism under the effect of reaction forces is prevented by the forces of friction between the housing 1 and the walls of the holes in the soil.

At the beginning of the forward stroke of the striker 2, its ports 7 put the front working chamberS in communication with the atmosphere. As the striker 2 moves forward and interacts with the bushing 8, at a certain preset distance from the extreme left (forward) position of the striker 2, its ports 7 put the front working chamber 5 in communication with the rear chamber 6 and, consequently, with compressed air supply.

Due to the recoil of the striker 2 from the front wall of the housing 1 and due to the pressure of the compressed air entering the front chamber 5 the striker 2 starts moving back (to the right in FIG. 1) because its working area is larger at the side of the front chamber 5 than it is at the side of the rear chamber 6.

After the ports 7 have been covered by the side surface of the bushing 8, the striker 2 overcomes the resistance of the compressed air in the chamber 6 and continues its movement to the right owing to the expansion of the air in the front chamber 5.

At the end of the backward stroke of the striker 2, it ports 7 put the front chamber 5 in comunication with the atmosphere through the ports of the row 12 and the discharge holes 13 of the bushing 8, through the ports in the row 17 of the slide valve 15, and through the discharge holes 14 in the flange 9 of the bushing 8. This is how the used air is discharged into the atmosphere.

Then the operating cycle of the mechanism is repeated over again.

When the mechanism is reversed for extracting it from the hole, first it is necessary to cut off the supply of compressed air. Then the spring 19 will move the slide valve 15 to the extreme left position (in FIG. 1) and the slide valve 15 will turn in the bushing 8 through a preset angle 01 (FIG. 4) owing to the movement of its projection 21 along the shaped recess 20 in the flange 9 of the bushing 8.

After turning on the supply of compressed air to the mechanism, the slide valve 15 will move to the extreme right position, compressing the spring 19 and simultaneously turning (owing to the movement of its projection 21 along the recess 20) through an angle org in the same diection as when the mechanism is shifted to operation in reverse.

Unilateral turning of the slide valve 15 (along arrow A in FIG. 4) is ensured by the movement of its projection 21 along the recess 20 to the angular displacement of the apieces 26 and 270i the respective zig-zag lines 24 and 25 which form the contours of the walls 22 and 23 of the shaped recess 20.

The ports in each row 16 and 17 of the slide valve 15 are arranged so that after the slide valve 15 has turned through an angle (a, 01 its ports in the row 16 get in line with the ports in the row 11 of the bushing 8 whereas the ports in the row 12 of the bushing 8 are covered by the side surfaces of the layer-diameter step of the slide valve 15.

After turning on the supply of compressed air, simultaneously with the movement of the slide valve 15 to the right, the striker 2 begins moving to the left until the compressed air begins to be delivered into the front chamber 5 from the rear chamber 6 earlier than it occurs during the forward operation of the mechanism owing to the alignment of the ports in the rows 16 and 11 with the ports 7 of the striker 2. As a result, the striker 2 will be stopped by the compressed air entering the front chamber 5 and, without striking the inside walls of the head ofthe housing 1, it will start moving to the right.

Owing to an increased volume of the front chamber 5 and delayed discharge of air from it (because the ports in the row 12 are covered and the air is discharged only after the ports 7 of the striker2 will have passed the larger step of the bushing 8) the striker 2 moving backward (to the right) will strike the flange 9 of the bushing 8 secured in the housing 1 of the mechanism.

Thus, the mechanism will move in the direction contrary to its working movement, i.e. it will move back through the already dug hole.

In order to shift the mechanism again from the reverse to forward operation, it is necessary to cut off the supply of compressed air then to turn it on again. In this case, as described above, the slide valve will turn twice through an angle equal to the sum of two angles a, and a so that the ports of the rows 12 and 17 will become aligned while the ports in the row 11 will be covered by the slide valve 15. Now the delivery of compressed air to the front chamber 5 will be controlled by the front face of the bushing 8 and the striker 2 will deliver blows at the inside wall of the front section of the housing, thus moving the mechanism forward.

It follows from the above, that the mechanism of the claimed design is reversed by momentarily cutting off the supply of compressed air to the mechanism.

The turning angle a, and a, of the slide valve 15 corresponding to one interval in the supply of compressed air may be selected so that one operation of the air valve will be sufficient for reversing the mechanism.

What we claim is:

l. A reversible air-punching apparatus for making holes in soil by compaction, comprising: a hollow housing for said apparatus having a pointed head portion; a reciprocable striker located within said housing adapted to strike the latter during reciprocation therein under the effect of compressed air; a forward variablevolume working chamber defined in said housing by said striker; a rear variable-volume working chamber located in the tail end section of said striker and communicating with said forward chamber through ports formed in said striker; a stepped-diameter air-feed bushing located in said rear chamber of the striker, said bushing having a flange for securing to the tail end section of said housing, said air-feed bushing having two parallel rows of ports formed on its larger diameter step portion interacting with said striker, and exhaust holes being formed on the face surface of said larger diameter step portion; a hollow spring-loaded slide valve being positioned within said air-feed bushing and having two rows of ports separated by a partition on a step portion thereof interacting with said bushing so as to be alternately alignable with the respective rows of ports on the bushing upon said slide valve being turned about its longitudinal axis; said slide valve being connected to said bushing by means of a projection extending along a closed shaped recess in the form of broken lines of identical configuration whereby each apex of one of said lines and an opposite apex of another of said broken lines are offset by an angle ensuring the turning of said slide valve in one direction during its axial movement. 

1. A reversible air-punching apparatus for making holes in soil by compaction, comprising: a hollow housing for said apparatus having a pointed head portion; a reciprocable striker located within said housing adapted to strike the latter during reciprocation therein under the effect of compressed air; a forward variable-volume working chamber defined in said housing by said striker; a rear variable-volume working chamber located in the tail end section of said striker and communicating with said forward chamber through ports formed in said striker; a stepped-diameter air-feed bushing located in said rear chamber of the striker, said bushing having a flange for securing to the tail end section of said housing, said air-feed bushing having two parallel rows of ports formed on its larger diameter step portion interacting with said striker, and exhaust holes being formed on the face surface of said larger diameter step portion; a hollow spring-loaded slide valve being positioned within said air-feed bushing and having two rows of ports separated by a partition on a step portion thereof interacting with said bushing so as to be alternately alignable with the respective rows of ports on the bushing upon said slide valve being turned about its longitudinal axis; said slide valve being connected to said bushing by means of a projection extending along a closed shaped recess in the form of broken lines of identical configuration whereby each apex of one of said lines and an opposite apex of another of said broken lines are offset by an angle ensuring the turning of said slide valve in one direction during its axial movement. 